Method of manufacturing circular sheet metal disks



Nov. 15, 1938. -H. SCHUSTER 2,137,099

METHOD OF MANUFACTURING CIRCULAR SHEET METAL DISKS Filed Feb. 7, 1935 i ====7=== Inventor D A ttomegs;

Patented I UN T D STATES This invention relates to a, method of manufacturing circular sheet-metal disks 'by rollin out a thicker disk of smaller diameter, such as I is describedin myiformer United States patent application Serial Number 747,239. The present, application is a continuation ih part of said formei'. and. co pending application. I In the method described in my said former application, the work-piece is rolled out between cylindrical rolls in directions at right. angles to one another, in succession, the reduction in I thickness of each intermediate form, which deviates from the, circular shape, being of the same percentage as the reduction'in thickness of [the immediately preceding circular form from which it was produced. According to my said former application, the thickjcircular work-piece isreducedand expanded into an elliptically shaped intermediate form by the first'pa'ss, then turned I .20 through 90 ,..and rolled again, the rolls on the second pass, however, having a suitably narrower pas'sa'ge. between them so that the same'percentage reduction will be produced as in the previous rolling. In this 'mann'er'the ellipse is 5 again converted into a 'disk of exact circular I shape. The procedure can be repeated as often as desired. I I I I o. According to an alternative'method of operation,.the work-piece which has become elliptical I after the first p'assis turned through an angle diffiering from 90 for further reduction in thick- I ness'and reconversion into the circular shape,

theoperation of turning the work-piece through this angle with accompanying further rolling 35 out being repeated until the minor axis of the ellipsefhas become equa l'to the major axis, that is to say, until the circular shape has again been attained. This method, as inthe case of 'the method of 'myfformer application, can be re- 40 peat'ed'as often asdesired. This rolling-out" of the work-piece in difierent radial directions may under certain circumstances have a favorf, able actiononthe texture of the finished disk, "particularly when the rolling is carried out in preferable. i

In accord thickness per cent, for example) is eflected as is the case in the preceding pass. Thisprocedure is then twice repeated in' case the tuma0 ingangle, as assumed, is 45. The work-piece is,

: responding rollings.

. times througha total angle{of- 135.l-

hape, either 25 I tne' {cold .state gi-iot rolling is; of course, also I j "possible and may, I under some circumstances; be i ncfthen, the second method I offoperation', the thick simmer initialwork-piece 5o is-firstrolled out to alfiefinitemeducedthickness and the 'ellipse'thus "iI rmedlias its major "axisiatright' angles to the axes of the"rolls;' it is" ""thenturne'd through an. angle of (forexampl) I about 45jand inf-this position 'isfed "through I 55' rolls; the passage between which is so dimen-" sionedthat the. same-percentage reduction in} thus,aftenitjhasjthe t time ceiv'ed'theeb i l shape; Whfi ihr t m s a l th q 45, and each time fed'ftlirough rolls which produce a percentage reductior'i inthickness equal to that produced hjIthe/ flrs "rolling out step. "5

The Work-piecenew; has a circular shape with a diameter greater tlianjthelarger diameter of the ellipse produced in"the', first" instance; fl

. Theoretically,.- tne.. angle through which the Work-piece has to lie turnedfeach .time'inorder to enable the Tellipt" a1. shape to converted back into the circular shape depends'zsolely upon the of "repetitions o'ffthe turning-opera- ,t ion' through this angle withfdf course, the cor- Only angles smallerthan i5 90, however, are of practical importance and. are so, chosen that refformation into the; circular shape is completedfafteronly a'few repetitions.

If in the "example just; referred to, an angle of hadbeen taken," then the work piece would have to be turned five 'times',i. e. =altogether through an angle M1509, while with -theassumed angle of 45 it would'onlyjhave tobe turned three I I f circular originally or as roduced by a cycle ofreducing operations wherein a I given angle of turning was employed, the stool; maybe reduced inthe-succeeding cycle by turning through-other angles. For example, it thestock wa's'turned through 3 Starting witli'a disk 'angl'esof 302145" or 'othersmall angles during a preceding 'cycle,1it may be'turned' 'through 90 I or] some other angle on thefsucceedi'ng cycle. Or" instead offturning each 'ti'me in 1a. cycle I through equal angles, the stock may be turned through 1a givenlangle or angles and finally through anfan'gle which is supplementary to the previous angle of turning. By employing supplementing angles at the en'd oiz the -cy cle the conversion back to"circular *form may be has-. tened." However, "in-'any-planofoperation the angles of turnln'gI must-be carefully selected according toj'the'law which I have-discovered and which will" be more fully stated hereinafter.

"* Againft-he percentage of reduction for-each "pass-1n a cycle may-also be varied if the herein. disclosed law ofieduction is followed..

The angle'ot urning, the percentageof reduction, and the" number of .passes in a cycle from circular shape to cir'cular shape may be ascer-' "tained either graphically or mathematically or by-:bothfmethods -combined in accordance with "the herein disclosedlaw i It-is .self evident-that th ate angle'throiigh which the work hasto be turned for converting to the circular shape from the elliptical shape will be smaller the nearer the angle of turning. for one pass approaches In the of angles which approach 0, there first of all takes, place an increase in the deviation from. w

the circular shape followed later by an approach and evening out to the circular shape. But such initial increase in the deviation from circular shape I find is a drawback and may be avoided if an angle is employed which lies in the neighborhood of 45 or over. Otherwise. that angle is to be preferred by the use of which the smallest possible total angle of rotation will represent a multiple of this angle without remainder, such as in the cases of the angles of 45 and given by way of example. In the case of a great many angles, the smallest possible total angle must be exceeded by further repetition if theotherwise remaining fraction. is not to be filled up by a supplementing angle of a difierent number of degrees which then has'to be ascertained while taking into consideration the necessary reduction in thickness.

In the accompanying drawing which illustrates practical applications of the invention:

Fig. 1 illustrates a rolling mill for reducing" e per cent.

I ellipse, the position or theangle bisectorsfwith;

Referring to Fig. 1 of the drawing, a circular disk of stock A is passed between the two upper .rolls B andG of a three-high rolling mill to produce the elliptical shape E. Thiselliptical shape is now turned through 90 and passed between the lower rolls C and D to .produce the exact circular shape F.

Referring to Fig. 2, i is the initial ellipse which has been produced by rolling out the circular work-piece indicated by broken lines; 2 is the intermediate stage, also elliptical, which results after the work-piece has been turned through 45; 3 is the further elliptical intermediate stage, and 4 is the finally obtained circular shape. The intermediate elliptical shapesare angularly displaced with respect to the immediately preced-- ing shape. The successive turnings of the work-- The major axis of the last ellipse however, as'

can be seen'from the drawing, has. only been angularly displaced, with respect to the direction of rolling, through an angle-0145.

The supplementing angle .above referred to:

cannot always be ascertained with exactness by a simple calculation. Take the case, for example, where an angle of 11, with a three times repetition, almost produces the circular shape, which for its complete formation requires a total angle of 11 which is somewhat greater than 311. By simple calculation, if one reckons from the first ellipse, a supplementing angle of b-3a must be chosen for the fourth pass. But

this would not be rigorously correct in every case since it has-been ascertained that f or .al-

tering the ratio between thetwo-axes of the respect to therollin'g axis has torbe taken into account, which inthe caseoi. acoi'nparatively small angle of rotation is difierent from that in the case of a larger angle of rotation. This requires a correction to the calculated supplementing angle which would ordinarily, in practice, be determined empirically although undoubtedly it could also be ascertained by calculation. 1

Since at suchrepetition of the turning operation and corresponding reduction in thickness, an increase in the size of the work-piece in the directions of-both axes of the ellipse takes place, and since we are only concerned with the obtaining of a larger and thinner final disk, it is not always necessary to effect a pass with a supplementing angle in order to reduce the number of passes. Thus, in such cases where a particular angle of turning alone enables a total angle of rotation to be attained which will produce a-circular shape after numerous repetitions of. the turning operation, this repetition can be chosen instead of the interposition of a supplementing angle. I

It is worthy of mention that there. is still a further possibility. The ellipse produced in the first instance by turning the work-piece through any desired angle and subsequently reducing it in thicknex by rolling, can first of all be converted into another ellipse, angularly displaced and of greater area, the work-piece being then so turned that the major axis of the ellipse lies -parallel to the rolls and rolled out in thisposition with a. diflerent percentage reduction in thickness, the extension taking place in a. direction at 90 with respect to the major axis as in my former patent application above mentioned. The altered percentage reduction in thickness must be so proportioned that a circular shape now results from the ellipse which was altered with respect to the original ellipse. According to the size of the preceding angle of rotation the percentage reduction, in thickness must be greater or less; that is to say, if the preceding angle of rotation was 45 it would have portion of the angle turned to the total turning of the previous angle or angles.

In any case where it is desired to produce a circular disk having definite diameter and definite thickness, when the precise treatment has been determined, one may ,ascertainby graphical or empirical preparatory work, or even purely by calculation backwards, what dimensions the initial work-piece must have. If the case occurs where theparticular position of the workpiece in the intermediate stages has to-be a's-.

certained with respect to the roll axes and the dimensions of the ellipse of'the individual intermediate shapes, then this can be facilitated by making the determination necessary to provide that the major axis of the particular ellipse to be rolled shall extend in the direction of the "bisector oi' the turning angle and that the magnitude of the ratios between the major and the -minoraxis of the respective ellipse can beset f down as ordinates on a sine curve.

in the case of my former patent application, the initial work-piece is preferably obtained by the reduction of a cylindrical block.

If value is not attached to th'eobtaining of an exact circle as final shape, that is to say, if an approximation to the circular shape Suflices and the exact circular shape isintended to be obtained by another further treatment, e. g. by cutting, then, of course, the described process can be terminated as soon as an ellipse is produced which does not depart excessively from the circular shape. In cases where the finished article is required to be of elliptical shape the process would, of course, not be continued until the circular shape were restored but would be terminated on the obtainment of the desired ellipti cal shape with the desired dimensions.

As already stated in my former patent application, a thick disk of elliptical shape can be employed as the initial work-piece and further operated upon accordingly until the desired cirone another, whereby the texture of the metal I is improved. Moreover, the' angle of rotation assistance when the stock is turned through differing from can be also utilized to obtain final forms which difier both from the circular shape and from the elliptical-shape; for by employing in the course of the process angles of rotation of diiferent size so that the reduction in thickness in the course of the process varies in percentage, not only the dimensions but also the shape of the final form can be influenced, particularlygif in addition aninitial work-piece is chosen which also deviates from the otherwise circular or elliptical shape. By graphical crempirical means which may also be assisted in part by calculation, it is possible in very many cases, in this manner, to obtain a final form of the desired dimensions which may be required at any particular time and for which the initial shape with its dimensions, as well as the shapes and It has previously been proposed, for example in the patent to Milliken No.- 1,561,346, November '10, 1925, to roll circular disksinto elliptical shape and then turn them through 90 and roll them again with the idea of again producing a circular shape. However, no rule of working is given which will assure the return to circular shape. One mustexperiment to determine the degree of reduction required to restore the elliptical disk to circular, shape. Of course, it has long been known, even inthe simple arts of rolling dough, putty, modeling clay and the like, that an elliptical shape could be restored to an approximately circularshape by rolling the el.- liptical shapealong its minor axis. But these known methods are experimental and give no definite assurance of producingan exact circular shape; moreover they refer only to the simple case of turning through. 90 and furnish no angles other than 90.

According to the present invention the alterations in the diskare performed under a rule or "law which will definitely assure the return to v To summarize what has been statedand illustrated by example hereinabove, the rule or law may be stated as follow: 1

Starting with a circular disk of uniform thickness, the stock is rolled a number of times in a cycle to change it from circular shape to G1- liptical shape and then back into exact circular shape. I v

The percentage of reduction and the principal axes of the ellipse formed in the first operation in the cycle, or first change from circular to elliptical shape, are takenas reference or datum points upon which subsequent operations in the cycle are based. I

The stock is worked in a straight line across its width. that is, along a diameter or axis, whether the operation is a continuous rolling action or otherwise. In any cycle from circularto-circular it is to be understood that the characteristics of the operating means, so far as side spread of stock is concerned, remain unchanged, or if changed that due account thereof be taken.

In any given cycle from circular-to-circular, the increment in length along one principal axis v of the first ellipse is made equal to the incretiple of the first.

The angle of turning for each rolling operation is preferably made} an aliquot part of 90 or of a simple multiple of 90, such as 180 or 270, usually-not over 180. The angle of turningwill be 90 or less, 'i. e. an acute angle, since the effect of turning more than 90 is the same as turning less. For example, the effect of turning obviously would be the same as turning 45, and of turning the same as turning 30.

When. turning by the same angle for each reduction in the cycle,v the total number of reducing operations required will bethe quotient of 90 divided by'half the angle of turning. For example the number of operations when turning 90 will be 2; for 45the number will be .4; for

30 the number will be 6; for 60 the number will be 3; and so on. The total angle ofturning from circular-to-circular will be the hum-'- When turning through angles which are not simple aliquot parts ofj90 or'of a simple multipie thereof and when turning through-supple menting angles to hasten thef return to-c'ireu lar shape, the basic rules are adhered'tofname 1y, that the last reduction is along the minor axis of the last ellipse and that the projected increments in reduction along the two principal axes of the first ellipse are made equal.

centages different from the percentage of reduction at the first operation, the basic rules are observed, namely that the last reduction is effected along the minor axis of the last ellipse, and thepercentages of reduction along the two principal axes of the first ellipse are made equal.

If one of the other regular forms produced in the cycle is desired instead of the circular form, the operations may be stopped with the desired form instead of being continued to produce the circular form. For any other shape, the nearest regular shape is taken and changed as required to produce the desired shape.

It will thus be seen that the invention provides a simple practicable and dependable method of reducing disk stock in such manner as to produce accurate predetermined circular shapes by a plurality of reducing and turning operations in which the turning may be through a number of different angles. This is possible because the invention furnishes a dependable rule or law by which to operate.

While certain embodiments of the invention have been described it is to beunderstood that the invention may have various embodiments within the limits of the prior art and the scope of the subjoined claims.

It is, however, an essential condition that the work-piece is not only turned but is, besides, passed through pairs of rolls, the passes whereof become progressively narrower by the same percentage, provided, that particular reasons do not give rise to a change of the rule regulating the decrease of the thickness of the sheetmetal, as has already been pointed out in the preceding pages and in which cases the width of said passes is otherwise regulated according to the change of the said rule. I claim:

l The method of manufacturing sheet metal disks by rolling out a disk between cylindrical rolls, comprising first rolling a circular disk work-piece into elliptical shape and then repeatedly turning it through an angle of which 90 is a multiple and further rolling it to reduce its thickness until' a circular shape is again obtained, each successive pass of the work-piece between the rolls, after the first pass, being so determined that the reduction in thickness producedthcreby will be of the same percentage as that of the first.

2. The method of manufacturing sheet-metal disks which comprises first rolling out a thicker circular disk of smaller diameter between cylindrical rolls whereby the work-piece is first reduced in thickness and changed into an elliptical shape, then repeatedly turning the workpiece and rolling it further to reduce it until it again becomes exactly circular, each turning being through the same angle of which 90 is a multiple and the width of the successive roll passes being so adjusted that the reduction in thickness obtained with each rolling with repeated turning through the same angle is of the same percentage as the reduction produced by the first rolling.

3. The method of manufacturing disks 01' malleable material, which comprises, rolling affircular disk along a first axis to thin it by a given percentage and to change it to a first elliptical shape; turning the disk through an angle which bears a. low-simple relation to one of the quarters of a circle, namely, 90, 180, 270, 360 degrees; rolling the disk along the new axis to reduce its thickness by the same percentage as at the first action; repeating'the turning and rolling after the first said rolling action until the disk is made substantially truly circular on the first approach to circular shape, that is, un-

the angles 15, 30, 45, 60, 90 degrees; rolling the disk along the new axis to reduce its thickness by the same percentage as at the first action; repeating the turning and rolling after the first said rolling action until the disk is made substantially truly circular on the first approach to circular shape, that is, until the minor axis of the first ellipse becomes equal to the major axis; and continuing the operations until the disk has the final size and thickness desired.

5. The method of manufacturing disks of malleable material, which comprises, rolling a circular disk along a first axis to thin it by a given percentage and to change it to a first elliptical shape, turning the disk through one of the angles 15, 30, 45, 60, 90 degrees; rolling the disk along the new axis to reduce its thickness by the same percentage as at the first action; and repeating the turning and rolling after the first said rolling action until the total number of rollings along different axes, including the first, equals the quotient obtained by dividing 90 degrees by halfthe angle of turning; the total angle of turning being equal to the total number of rollings, minus one, multiplied by the angle of turning, whereby-the disk is made substantially truly circular by making the minor axis of the first said ellipse equal to the major axis thereof before further rolling operations are performed on the disk, for the purposes set forth.

6. The method of manufacturing disks of malleable material, which comprises, rolling a circular disk along a first axis to thin it by a given percentage andto change it to a first elliptical shape; turning the disk through one of the angles 15, 30, 45, 60, 90, degrees; rolling the disk along the new. axis to reduce its thickness by the same percentage as at the first action;

and repeating .the turning and rolling after the first said rolling action until the total number of rollings along different axes, including the first, equals the quotient obtained by dividing 90 degrees by half the angle of turning; the total angle of turning being equalto the total number of rollings, minus one, multiplied by the angle of turning, and the last rolling to return the disk to circular shape being effected along the minor axis of the last formed ellipse, where- -by the disk is made substantially truly circular by making the minor axis of the first said ellipse equal to the major axis thereof before further rolling operations are performed on the disk, for the purposes set forth.

HANS SCHUSTER. 

